The appearances remained unexplained until they were tied together in the toon DNA Evidence, in which it was revealed that Strong Bad had broken intoMarzipan's house and dropped a vial of green DNA evidence in her couch. Marzipan found it and brought it to be analyzed by Bubs, but she only got back another vial marked "tampered with". Bubs had sold the actual DNA evidence to Strong Bad in a snow cone, in lieu of green apple flavoring, and had most likely then refilled the vial with "purple" flavored snow cone syrup and given it back to Marzipan. Strong Bad had deliberately deprived Bubs of green apple flavoring in order to get the DNA evidence, which he hoped to use for genetic experiments involving The Cheat. Homestar Runner drank the melted-snow-cone DNA evidence, thinking it was Mountain Dew, and he promptly spat it out on The Cheat, who then dried himself off with a towel. The towel was used by Coach Z to do his janitorial work at the office, when it inexplicably disappeared. It was revealed at the end that the evidence was Strong Sad's DNA, and Strong Bad had intended to use it to find out if Strong Sad was "part elephant or part hippo or something". Strong Sad was extremely pleased that no one found out, and he recovered the DNA by stealing the towel from Coach Z's cart. He hid the DNA evidence in the box with the rest of his secrets. While Homsar witnessed this revelation, it seems unlikely he will be able to communicate it to anyone.

According to The Brothers Chaps in the DVD commentary for DNA Evidence, it started as a one-off joke in strong badathlon. They decided to call back to the joke when they found an opportunity to use it in the next email, unnatural. By that point, they had started putting references in each following email until they had released a full-length cartoon based around these "weird little snippets". The Brothers Chaps had apparently started talking about a cartoon after the third appearance in the movies.

DNA is often used in forensic science deduction to connect bodily fluids or tissue found at a crime scene to a particular individual. It may also be used to identify a corpse.